1. Field of the Invention
Provided is a high temperature paper structure comprised of two outside layers and at least one inside layer. The two outside layers are generally comprised of substantially cellulosic pulp fiber, and the inside layer is comprised of cellulosic pulp fiber, a high temperature fiber and a polymeric binder. The paper structure can be used as a high temperature E-board for application in transformers, and offers enhanced thermal resistance.
2. Description of Related Art
High temperature E-board is used in transformers and performs two functions. First, the E-board provides electrical insulation. This keeps the coils in the transformer from short circuiting. Secondly, the board provides mechanical strength. When there is a large passage of current through the transformer, there is force on the layers of the coil to move the board, which is glued to the coils. The glueing of the board to the coil keeps the various coils from telescoping. Each coil acts like a solenoid and tries to move. It is the E-board which prevents this telescoping.
Improving the mechanical strength of the E-board would aid in avoiding problems with telescoping coils. Having a reinforced E-board to strengthen the paper would help to provide the necessary mechanical strength. The paper, however, would have to be made in an efficient and effective manner.
There is also interest in increasing the temperature resistance of E-board for use in transformers so that a less expensive transformer could be designed. By reducing the diameters of the wires in a transformer, the coils would become smaller. Smaller coils require smaller cores and smaller metal containers. Smaller containers hold less oil, and this means that less copper for the wire, steel for the cores and oil for the insulation are needed. Because of the thinner wire, however, the transformer would have more electrical resistance and would run hotter. Thus, the E-board would have to exhibit enhanced thermal resistance before such a transformer would be practical.
A paper which exhibits such enhanced thermal resistance, as well as enhanced mechanical strength would allow the industry to design transformers which can recognize the economic benefits and performance benefits discussed above.
Accordingly, it is an object of the present invention to provide a paper structure which exhibits enhanced thermal resistance.
Yet another object of the present invention is to provide a paper structure which exhibits enhanced mechanical strength.
These and other objects of the present invention will become apparent to the skilled artisan upon a review of the following description, and the claims appended hereto.